Inertia operating member for automatic firearms



l.1. L. LOCHHEAD INERTIA OPERATING MEMBER FOR AUTOMATIC FIREARMS April 12, 1949.

Filed NOV. 2l, 1946 2 Sheets-Sheet 1 Nw im W, @MM w N. m mw mm wu M m@ .L .I QN 5m: n. w. 9. A .my /Nb N Gm MN MN m @n MN J0 a, ,um mn a Q E:

' April 12, 1949 J. LocHHEA 2,466,902

INERTIA OPERATING ME ER FOR AUTOMATIC FIREARMS Filed Nov. 21, 1946 2 Sheets-sheet 2 ZZ zu 'y Z i0 17 Z/y g@ /////f/// /g' Patented Apr. 12, 1949 IN ERTIA-.QPERATIN Gr.MAEMBERFFORY AUTOMATIC FIREARMS John L. Lochhea'd; Springfield; Mass, assignor'to` Olinv Industries; Inca New-Haven, Conn., azcor l porationioffDjelaware ApplicationNovember 21, 1946, SerialNo. 711,242

9 Claims.l 1

The present invention relates in generalitoi rearms andfmore especiallyv to asemi-automatici or fully automatic lirearm` having a ixedbarrel. andrecoil-actuated mechanism for operating the breechblock.

An object of the invention is to provide an; automatic rearm having a xed'barrel'with improved mechanical' means, asdistinguished from, gasfoperated means, responsive to the recoil` ace tion ofthe iirearmrwhen-red', to automatically actuate. the breechblock operating-mechanism.

A further object of the invention. islto provide. an automatic firearm havinga iixedbarrel` with improved recoil-actuated `nreechblock operating.- mechanisni mountedrinl a compactimanner. withinA the forestock ofthe 'rearm..

A further object of the inventionis to` provide anv improved automatic rearm having a fixed. barrel in which the breechblock is automatically operated by recoil-actuated: mechanismlwhich.is` of relatively-simple construction, wholly mechanical in nature and ofrelatively, few parts, all"of:' which are sturdy and. oier high resistance; to

wear.

A. still furtherobjectof the invention'ist'aprovide an automatic firearm. havinga xedbarrel with an inerta-weightif'or'operating the breechblock; the-inertia-weight'beingadapted tozuse'the' initial recoil force of"` the rearm' when` red to hold the breechblock'in locked. position and'after: the force of4 the recoilhas spentitself to unlockv the breechblock and" move it rearwardly in thei receiver.

With thel abovei and' other objects in View; as will appear to v thosev skilledv in" the,I art` from the` present disclosure, this invention includesl allI features in the-said disclosurel which are novel over the prior art.

In the accompanying drawings; in1 which-'centain modes of carrying out'the present invention' are shown for illustrative purposes:l

Fig. 1- is a side elevation partlyin-section' ofj theimproved firearm of! this-- invention;I thed breechblock. being inA its breech-closingposition;

Fig; 2=isa side-elevation-of therearm similar to Fig. 1 but immediately afterthe gun has'beenr discharged, showing the displacement of the gunl rearwardly with' respect to the1ii1ertiabl`ock of" the breechblock: act'uatingemechanism;

2y now open, the breechblock having'been'moved'to itsrearmost position inthe receiver'bythe rearward movement of Ethe inertia-block;

' the rear-ends respectivelyY of' the barrel' lli and tubular magazine' I8, th'elatter being secured in ts'aperturel l'by a threaded'connection. The;

rear endofthe barrel IIzhas a free t in itsapere ture I5' of the front wall Ill`l of," the receiver and embodies asubstantia'lly U.shaped barrel-exten.- sionn I9" which extends'rearwardlyinto a corre.- spondingly-shaped'Ielieferecessv 2 U 'formediin the underside andinner walls respectively of the top l2y andL sides |3--of' thereceiver; the rear end of' the barrel-extension being adapted. to be held securelyin abutting engagement with a substantially-square shoulder 2| of the relief-recess 20- hy-fmeans of the-takedown-screw hereinafter'described.l The top wall of the barrel-extension I9 is provided with a longitudinally-extendingv substantially-rectangularslot122g the rear endof which is provided" witha beveledshoulcler 23; as shown in Fig. 1', adapted to be'engaged by a locking-lug- 2'4on-the breechblock 25-tolock the latter in1 breech-closingposition, as hereinafter desoribed As-shown in Fig.' ll; alongitudinal'slot 26is `proviclediin one side `of thebarrel-extension coincidenti with an ejection-portv 2Y formed in oneside I3 of the-receiverfor permitting fired',

cartridgesto be ejected from*t'he'receiver.` The bottom of the receiver-I Iisan open'V slot whichis adaptedto-be-partially closedl in a conventional` manner by a-v triggerplate indicated generally at 28^lin1which=is= mountedthe ltrigger 29 and'related' Eig;v 3is,:sir'nilarl toFig. 1 exceptfthe'factonis" 50 rihgfmechanism'- (not shown) for ringaY car'- tridge. The usual opening in the bottom of the receiver forwardly of the end of the triggerplate is left to permit the cartridges to be loaded into the rear end of the tubular magazine I8. The bottom of the receiver II is also provided with a rearwardly-projecting tongue 30 having an internally-threaded aperture to receive the threaded end of a stud 3l of a stock-screw 32, the stud 3l and screw 32 being mounted in a longitudinal aperture of the stock 33 and arranged in the usual manner to secure the latter rmly to the rear end of the receiver. The stock 33 is also provided with a second longitudinal aperture 34 which is adapted to accommodate an actionclosing spring 35, the rear end of which seats against the bottom of the aperture 34. The forward end of the action-closing spring carries a spring-pilot 36 which is sldably mounted in the forward end of a guide-tube 31, the latter being, in turn, secured in the open end of the stockaperture 34. The front face of the spring-pilot 36 comprises a shallow concave recess in which the rounded rear-end of an action-link 38 is adapted to seat, the forward end of the link 38 being pivotally connected to the breechblock 25, as described below.

The breechblock is a substantially-solid rectangular block, the top of which has a radius corresponding substantially to the radius of the top wall of the barrel-extension `and embodies the usual firing-pin 39 and extractorand ejectormembers (not shown). The breechblock is arranged in a conventional manner to reciprocate longitudinally in the receiver and to have pivotal movement therein in the vertical plane thereof at both the forward and rearward extremities of its excursion, its pivotal movement at the forward end of the receiver being adapted to engage and disengage the locking-lug 24 of the breechblock with the beveled shoulder 23 of the fixed barrelextension for locking and unlocking the breechblock in and from breech-closing position respectively, in the manner well known in the art.

Referring to Figs. 4 and 7, a clearance-notch is provided on the underside of the breechblock and forms spaced parallel anges on opposite sides thereof as indicated generally at 4I, their lower edges 43 being adapted, as hereinafter described, to cooperate with suitable slide-action mechanism to hold the breechblock in breechclosing position immediately following the firing of a cartridge so as to provide for a delayed action in opening the breech. The edges 43 of the flanges 4I terminate in the forward edges 44 of a camslot 45 which comprises the aforesaid pair of spaced parallel front edges 44 and a pair of spaced parallel rear edges 46 in parallel relationship thereto, the cam-slot 45 extending rearwardly and upwardly in a depending-lobe 41 formed at the rear end of each flange 4 I The action of the breechblock is controlled in general by engagement of a transverse action-pin 4B in the cam-slot 45 and with the edges 43 of the breechblock. To this end, a pair of action-bars 49 lare slidably mounted in suitable guide-slots 50 in the front wall I4 and side walls I3 of the receiver, the bars 49 being adapted to extend rearwardly into the receiver on opposite sides respectively of the breechblock. Each end of the action-pin 48 has a drive fit in a corresponding aperture in the rear end of its respective action-bar 49, as shown clearly in Fig. 6, and is adapted, in its normal position, that is to say, when the breechblock is in breech-closing position prior to ring a cartridge, to engage the edges 43 of the breechblock adjacent the rear extremities thereof, as shown in Fig. l, the action-pin 48 serving thus to prevent pivotal displacement of the breechblock out of breech-closing position.

Referring to Fig. 1, the transverse action-pin 4B also constitutes the means for pivotally connecting the forward end or wrist 5| of the actionlink 38 to the breechblock, the wrist 5I being located in the aforesaid clearance-notch in the underside of the breechblock and designed to make a nice t between the spaced parallel flanges 4I thereof. Referring to Fig. 4, the flanges 4I of the breechblock and, in particular, the lobes 41 thereof, are shown to be accommodated in clearancespaces formed between opposite sides of the link- Wrist 5I and the corresponding rear ends of the respective slide-action bars, and in accordance with this construction the cam-surfaces 44 and 46 respectively of the cam-slot 45 are .adapted to be operatively engaged by those portions of the Iaction-pin 48 which extend across the aforesaid clearance-spaces.

W'hen the breechblock is in its forward breechclosing position in the receiver, the lug 24 of the breechblock is adapted to lockingly engage the shoulder 23 of the xed barrel-extension and is held in engagement therewith by engagement of the action-pin 48 with the edges 43 of the breechblock. The breechblock is adapted to be unlocked and moved rearwardly in the receiver by moving the action-pin 48 rearwardly relative to the breechblock, so as to displace the pin from the edges 43 into the cam-slot 45 and, in particular, into engagement with the rear edge 46 thereof, thereby pulling the rear end of the breechblock downwardly so Ias to disengage the lug 24 from the shoulder 23, whereupon the breechblock may be moved rearwardly in the receiver. During the rearward movement of the breechblock, the link 38 which connects the breechblock 25 to the closing-spring 35 compresses the latter, as indicated in Fig. 3. At the end of the rearward excursion of the breechblock, the action-pin 48 of the link 38 is biased to move forwardly, by the force of the compressed closing-spring 35, into engagement with the forward edge 44 of the cam-slot 45, as a consequence of which the breechblock is moved forwardly into breech-closing position.

The improved means of this invention for moving the action-pin 48 rearwardly to unlock the breechblock and initiate its rearward excursion, comprises recoil-actuated means, indicated generally at 52, consisting of an inertia-weight or -block 53 cooperatively associated with a recollunlocking spring 54, as hereinafter described. Referring to Fig. 6, the inertia-weight 5,3 comprises a longitudinal block substantially rectangular in cross section, the underside 55 of which is substantially semicylindrical in shape and concentric with the semicylindrical inside wall of the forestock 56. The upper surf-ace of the inertia-block comprises a. longitudinal, substantially-semicylindrical recess 51 to provide clearance for the underside of the barrel I1, as shown in Fig. 5. Extending longitudinally through the inertia-block is a cylindrical aperture 58, the diameter of which may be slightly greater than the diameter of the tubular magazine I8, whereby the inertia-block may be mounted on the magazine and moved freely back and forth thereon. To this end, the forward end of the magazine is adapted to be supported in the axially-aligned aperture 59 of a depending barrel-lug 60 formed integrally or otherwise secured to the forward end of a barrel. The forward end of the magazine has a free t in the aperture 59 of the lug 60 `and is adapted to be secured therein by a takedown screw 6|'. The latter comprises a threaded shank 62 adapted to be screwed into the forward end of the magazine; .and a shoulder 63 arranged to be brought into abutting engagement with the front face ofthe barrel-lug 6i) as the screw 6l is tightened; Byvr tightening the take-down screw Gl, the barrel-lug 6U and barrel l1 are forced rearwardly relative to-the magazinel i8 thereby forcing the end of the barrel-extension 'against the shoulder 2l of the relief-recess in the receiver to firmly secure the barrel therein. At the same time, the forward end of the magazine I8 is rmly secured in the aperture of the barrel-lug 6i). It will be understood that by unscrewing the takedown screw 6| and moving the breech-block rearwardly out of locking engagement with the barreleXtension i9, the barrel may be readily withdrawn from the receiver.

1t should be noted also that the forestock 56 is xedly secured on the underside of the barrel by the take-down screw 6l which when tightened up is adapted to bind the opposite ends of the forestock between the forward face of the front wall i4 of the receiver and the rear face of the barrel-lug 60. Whenever the take-down screw is loosened, the forestock 56 may be readily removed.

Extending rearwardly from the front end of the tubular magazine and formed in the top wall thereof, is a substantially-rectangular relativelynarrow slot Gli which is slightly greater than onethird the over-al1 length of the tubular magazine and terminates in a transverse shoulder 65.

Referring again to Fig. 6, at the front end of the inertia-block is a longitudinal slot 66 which intersects the cylindrical aperture 58 and the semicylindrical recess 51 of the inertia-block and terminates in a transverse shoulder 61. The width of the slot 66 corresponds substantially to the width ofthe slot 64 of the tubular magazine and about one-third its length, the two slots 5t respectively being arranged in the same vertical plane, as sho-wn in Fig. 5. Suitably secured to the rear end of the inertia-block and on opposite sides thereof adjacent its top edges, are the forward ends of the slide-action bars, each of which extends rearwardly on opposite sides of the tubular magazine within the encompass of the fixed forestock 56. The tubular magazine is provided adjacent its forward end with a plug 83 which is secured by a pin $9 in the magazine adjacent the transverse shoulder 65 thereof. The plug 68 constitutes a stop for the forward end ofthe magazine-spring 1D, the rear end of which .is accommodated in the usual manner in an apertured magazine-follower TI, the latter being adapted to move cartridges from the magazine rearwardly intov the receiver from whence they are automatically loaded into the chamber of the barrel by conventional carrier-means (not shown) acting in conjunction with the forwardlymoving breechblock.

Supported in the forward end of vthe tubular magazine is the recoil-unlocking spring 54, the forwardr end of which engages the takedownscrew iii. The rear end of the recoil-unlocking spring is received in the longitudinal aperture of a pilot-member 'i2 whichv is slidably mounted in the forward end of the tubular magazine and has a guide-finger i3 which is. arranged to extend up- 6, unlocking spring 54 into engagement with the transverse shoulders 65 and 61 thereof.

The entire assembly, including the tubular magazine, the inertia-block and the recoil-unlocking spring, is adap-ted to be enclosed withinl the forestock 55 of the firearm, the stock being suitably secured to the magazine in any conventional manner.

I'n order to initially load the firearm, it is proposed to provide a manually-operable handle 'I4 for opening the breech and loading a cartridge into the chamber of the barrel. Referring to Fig. 6, the handle 'M is arranged to be secured tor one of the slide-action bars 49 and to project outwardly through a longitudinal slot 15 in the adjacent sidei3 of the receiver. By grasping the handle ill and pulling it rearwardly, the rearm may be loaded, preparatory to ring the rst cartridge, following which the rearm automatically ejects the red cartridge and reloadsi, as described below..

The operationV of the rearm may be described briefly as follows: With the breechblock 25 in its forward breech-closing position, hereinabove referred to as its normal position, as shown in Fig. 1, its locking-lug 24 is in locking engagement with the shoulder 23 of the fixed barrel-extension le, having been raised into locking engagement therewith by the force of the closing-spring 35 acting on the action-link 38. The transverse action-pin [i8 is shown engaged on the edges d3 on the underside of the breechblock adjacent the rear ends thereof. With the parts in this relationship, the forward end of the inertia-block is in engagement with the upwardly-extending guide-finger I3 of the spring-pilot member T2, the latter being flxedly held against the transverse shoulder 65 of the magazine slot by the force of the recoil-unlocking spring 54. When the gun is discharged, the force of its recoil moves the gun, including the barrel, receiver, magazine, and recoil-unlocking spring and breechblock assembly, rearwardly with respect to the inertiablock and its attached action-bars 49, the inertiablock remaining substantially immobile and in continuous engagement Iwith the nger 'i3 of the recoil-spring pilot l2. As a consequence of this action, the recoil-unlocking spring 56.k is compressed, due to the relative movement of the spring 515 and inertia-block. Since the transverse action-pin 48 is secured to the rear ends of the slide-action bars AS of the immobile inertia-block 53, the pin is moved forwardly, relatively speaking, in continuous engagement with the edges 43 of the breechblock, thereby positively holding the breechblock in breech-closing position immediately following the ring of the cartridge. After the force of the recoil has spent itself, the force of the compressed recoil-unlocking spring 54, acting on the spring-pilot member 12, thereupon drives the inertia-block 53 rearwardly on the tubular magazine I3, the spring-pilot F2 bringing up against the transverse shoulder 65 of the slot 64 in the tubular magazine. The rearward movement of the inertia-block thus displaces the transverse action-pin 48 of the slide-action bars rearwardly out of engagement with the edges i3 on the underside of the breechblock into the camslot 45 and particularly in camming engagement with the rear edge 46 thereof. Thereupon, the rearwardly-moving action-pin 48 forces the locking-lug 2li of the breechblock o-ut of engagement with the shoulder 23 of the barrel-extension, and thecontinued rearward movement of the inertiablock carries the breechblock. rearwardly in the receiver to its rearmost position, as indicated in Fig. 3. During its rearward excursion, the link 38 of the breechblock compresses the closingspring 35 in the stock 33, following which the breechblock is advanced to its forward position in the receiver by the force of the compressed closing-spring 35. During its forward movement, a cartridge which has been moved into the receiver from the magazine is lifted up into the path of the breechblock and engaged and moved thereby into the chamber of the barrel. Simultaneously, the slide-action bars 49 move the inertia-block 53 forwardly on the tubular magazine I8 until its forward end again engages the upwardly-projecting finger 13 of the recoil-spring pilot 12. The elements of the firearm are again in normal firing position.

Although the firearm structure, and in particular the recoil-actuated means described above for automatically operating the breechblock, is wholly successful, it is within the purview of the invention to provide for the nice balance of the firearm by proportioning the weight of the inertia-means between the inertia-block 53 in the forestock 56 and the spring-pilot 36 or equivalent member in the buttstock 33. It will be appreciated that these elements are cooperatively engaged during recoil and, hence, the effective weight of the inertia-means equals the combined weight of the spring-pilot 36 and the inertia-block 53. Consequently, by distributing this combined weight in the proper ratio as, for example, by modifying the inertia-block 53 and spring-pilot 36 of the present embodiment so that the two are of substantially equal weight, any tendency for the firearm to be muzzle heavy or to have a heavy buttstock may be successfully obviated, thus insuring a nicely balanced firearm.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

l. In an automatic firearm: a receiver; a barrel secured to said receiver; a breechblock in said receiver movable into and out of locked position therein; and recoil-energized means to move said breechblock comprising an energystoring member and an inertia-member connected therewith, said inertia-member having an element in slidable engagement with said breechblock and movable forwardly relative to said breechblock to hold said breechblock locked in breech-closing position immediately following the firing of a cartridge and simultaneously to store energy in said energy-storing member, said energy-storing member being arranged thereafter to move said inertia-member and said element rearwardly relative to said breechblock so as to unlock said breechblock and move it rearwardly in said receiver out of breech-closing position.

2. In an automatic firearm: a receiver; a barrel secured to said receiver; a breechblock in said receiver movable into and out of locked position therein; recoil-energized means to move said breechblock comprising an energy-storing member and an inertia-member connected therewith, said inertia-member having an element in slidable engagement with said breechblock and movable forwardly relative to said breechblock to hold said 8 1 breechblock locked in breech-closing position immediately following the ring of a cartridge and simultaneously to store energy in said energystoring member, said energy-storing member being arranged thereafter to move said inertiamember and said element rearwardly relative to said breechblock so as to unlock said breechblock and move it rearwardly in said receiver out of breech-closing position; and yieldable-means connected with said inertia-member and independent of said energy-storing member to restore said breechblock to breech-closing position.

3. In an automatic firearm: a receiver; a barrel secured to said receiver; a breechblock in said receiver movable into and out of locked position therein; recoil-energized means to move said breechblock comprising an energy-storing spring, and an inertia-block connected therewith, said inertia-block having an element in slidable engagement with said breechblock and adapted to remain substantially immobile relative to said breechblock on firing a cartridge so as to hold said breechblock locked in breech-closing position immediately thereafter and simultaneously to store energy in said energy-storing spring, said energy-storing spring being arranged subsequently to transmit its stored energy to said inertia-block thereby to move said inertia-block and its element rearwardly relative to said breechblock so as to unlock said breechblock and move it out of breech-closing position; and yieldablemeans connected with said inertia-block and independent of said energy-storing spring to restore said breechblock to breech-closing position.

4. In an automatic firearm: a receiver; a barrel secured to said receiver; a breechblock in said receiver movable into and out of locked position therein; recoil-energized means to move said breechblock comprising an energy-storing spring, and an inertia-block connected therewith, said inertia-block having an element in slidable engagement with said breechblock and adapted to remain substantially immobile relative to said breechblock on firing a cartridge so as to hold said breechblock locked in breech-closing position immediately thereafter and simultaneously to store energy in said energy-storing spring, said energy-storing spring being arranged subsequently to transmit its stored energy to said inertia-block thereby to move said inertia-block and its element rearwardly relative to said breechblock so as to unlock said breechblock and move it out of breech-closing position and stopmeans arranged to be engaged by said energystoring spring following the transmission of its energy to said inertia-block to disengage said energy-storing spring from said rearwardly moving inertia-block.

5. In an automatic firearm: a receiver; a barrel secured to said receiver; a breechblock in said receiver movable into and out of locked position therein; recoil-energized means to move said breechblock out of breech-closing position comprising a breechblock-actuating slide having a breechblock-contacting pin slidable forwardly and rearwardly relative to said breechblock, an energy-storing spring, and an inertia-block connected to said breechblock-actuating slide and said energy-storing spring, said inertia-block, actuating-slide and breechblock contacting pin being adapted to remain substantially immobile relative to said breechblock on firing a cartridge so as to hold said breechblock locked in breechclosing position immediately thereafter and simultaneously to store energy in said energystoring spring, said energy-storing spring being arranged subsequently to transmit its stored energy to said inertia-block thereby to move said inertia-block, said breechblock-actuating slide and said breechblock-contacting pin rearwardly relative to said breechblock so as to unlock said breechblock and move it out of breech-closing position; stop-means arranged to be engaged by said energy-storing spring following the transmission of its energy to said inertia-block to disengage said energy-storing spring from said rearwardly-moving inertia-block; and spring-loaded means in engagement with said breechblockactuating slide to operate said breechblockactuating slide so as to restore said breechblock to breech-closing position and return said inertia-block into cooperative engagement with said energy-storing means.

6. In an automatic firearm: a receiver; a stock secured to one end of said receiver; a barrel secured to the opposite end of said receiver; a breechblock in said receiver movable into and out of locked position therein; a breechblockactuating slide having a breechblock-contacting pin slidable forwardly and rearwardly relative to said breechblock; yieldable-means mounted in said stock arranged to engage the corresponding end of said breechblock-actuating slide normally to move said breechblock forwardly into breechclosing position; and recoil-energized means to unlock and move said breechblock out of breechclosing position comprising an energy-storing spring xedly supported on the underside of said barrel adjacent the forward end thereof, and an inertia-block slidably supported on the underside of said barrel and connected at its rear end to said breechblock-actuating slide and at its opposite end with said energy-storing spring, said inertia-block, actuating-slide and breechblock-contacting pin being arranged to remain substantially immobile relative to said breechblock on firing a cartridge so as to hold said breechblock locked in breech-closing position immediately thereafter and simultaneously to store energy in said energy-storing spring, said energy-storing spring being arranged subsequently to drive said inertia-block, said breechblockactuating slide and said breechblock-contacting pin rearwardly relative to said breechblock so as to unlock said breechblock and move it out of breech-closing position, said rearwardly-moving linertia-block and slide being adapted to store energy in said yieldable-means whereby the latter is energized to return said breechblock to breechclosing position.

7. In an automatic firearm: a receiver; a stock secured to one end of said receiver; a barrel secured to the opposite end of said receiver; a breechblock in said receiver movable into and out of locked position therein; a breechblockactuating slide having a breechblock-contacting pin slidable forwardly and rearwardly relative to said breechblock; yieldable-means mounted in said stock arranged to engage the corresponding end of said breechblock-actuating slide normally to move said breechblock forwardly into breechclosing position; recoil-energized means to unlock and move said breechblock out of breech-closing position comprising an energy-storing spring Xedly supported on the underside of said barrel adjacent the forward end thereof, and an inertia-block slidably supported on the underside of said barrel, and connected at its rear end to said breechblock-actuating slide and at its opposite end with said energy-storing spring, said inertia-block, actuating-slide and breechblockcontacting pin being arranged to remain substantially immobile relative to said breechblock on firing a cartridge so as to hold said breechvblocklocked in breech-closing position immediately thereafter and simultaneously to store energy in said energy-storing spring, said energystoring spring being arranged subsequently to drive said inertia-block, said breechblock-actuating slide vand said breechblock-contacting pin rearwardly relative to said breechblock so as to unlock said vbreechblock and move it out of breech-closing position; andstop-means arranged to be engaged by said energy-storing spring following the transmission of its energy to said inertia-block to disengage said energystoring spring from said rearwardly-moving inertia-block, said rearwardly-moving inertiablock and slide being adapted to store energy in said yieldable-means whereby the latter is energized to return said breechblock to breechclosing position.

8. In an automatic rearm: a receiver; a barrel secured to said receiver; a tubular magazine supported on the underside of said barrel; a breechblock in said receiver movable into and out of locked position therein; recoil-energized means to move said breechblock comprising an energy-storing spring secured in the outer end of said tubular magazine, a spring-pilot in engagement with said energy-storing spring and slidably mounted in said tubular magazine and an inertia-block slidably supported on said tubular magazine said inertia-block having a breechblock-contacting pin at one end in slidable engagement with said breechblock, the opposite end of the latter being engaged with the pilot of said energy-storing spring, said inertia-block and said contacting-pin being arranged to remain substantially immobile relative to said breechblock on ring a cartridge so as to hold said breechblock locked in breech-closing position immediately thereafter and simultaneously move said springpilot forwardly relative to said energy-storing spring so as to compress said energy-storing spring, said compressed energy-storing spring being arranged thereafter to drive said springpilot, said inertia-block and said contacting-pin rearwardly thereby to unlock said breechblock and move it rearwardly out of breech-closing position; and yieldable-means cooperatively associated with said breechblock to restore said breechblock to breech-closing position.

9. In an automatic firearm: a receiver; a barrel secured to said receiver; a tubular magazine supported on the underside of said barrel; a breechblock in said receiver movable into and out of locked position therein; recoil-energized means to move said breechblock comprising an energy-storing spring secured in the outer end of said tubular magazine, a spring-pilot in engagement with said energy-storing spring and slidably mounted in said tubular magazine and an inertia-block slidably supported on said tubular magazine said inertia-block having a breechblock-contacting pin at one end in slidable engagement with said breechblock, the opposite end of the latter being engaged with the pilot of said energy-storing spring, said inertia-block and said contacting-pin being arranged to remain substantially immobile relative to said breechblock on firing a cartridge so as to hold said breechblock locked in breech-closing position immediately thereafter and simultaneously move said spring-pilot forwardly relative to said energy-storing spring so as to compress said energy-storing spring, said compressed energystoringr spring being arranged thereafter to drive said spring-pilot, said inertia-block and said contacting-pin rearwardly thereby to unlock said breechblock and move it rearwardly out of breech-closing position; stop-means in said tubular magazine arranged to stop the rearward movement of said pilot thereby to disengage the spring-loaded pilot from said inertia-block; and spring-loaded means in engagement with said breechblock arranged to restore said breechbloek to breech-closing position and to return said inl2 ertia-biook into engagement with said springpilot.

JOHN L. LOCHHEAD.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 10 Number Name Date 802,033 Freeman Oct. 17, 1905 870,719 Freeman Nov. 12, 1907 y 935,237 Savage Sept. 28, 1909 

